CHES (Cumulative Hydrological Effects Simulator) estimates the net changes to the flow regime throughout a catchment due to multiple water use schemes. It also quantifies the consequences for both the overall availability and reliability of the water resource and the residual flows that determine the in-stream environmental effects such as physical fish habitat availability.
CHES provides water resource managers with cost-effective, rapid, and flexible assessment of the cumulative effects of complex surface water allocation scenarios. It can even incorporate future climate change.
NIWA's new CHES (Cumulative Hydrological Effects Simulator) software tool predicts how water flows in a catchment will change with multiple water uses (e.g. direct abstractions or storage reservoirs) and what the consequences will be to in-stream ecosystems and reliability of water-take.
CHES is easy to use and an essential tool for understanding the interplay of existing and new abstractions. It enables you to analyse the simulated or measured time series of residual river flows, and water takes, for user-specified scenarios.
User Interface - Guide to the main CHES window.
CHES can simulate the following abstractions:
CHES is catchment-based, and can generate surface water flows and dependent attributes as catchment averages, reach averages and reach time series. It requires the mean daily, natural flow time series to be supplied for each reach of the catchment that is to be examined.
CHES incorporates modelled river-flow time series for New Zealand's half-million reaches, and includes user-specified abstraction and storage options. It calculates the effects of water use by combining numerical water routing with operating rules. For example, placing a dam into a catchment uses a digital elevation model to calculate reservoir geometry and storage dynamics.
There are a number of data requirements to run CHES in the ArcGIS environment, these can be divided into the following four groups:
The ArcGIS data layers required include: existing takes, new takes, storage dam, streams, DEM and HydroEdge. Much of this data can be supplied by NIWA. The specific data required to run the CHES simulation includes flow data, slope, REC meta data and other reach parameters, again much of this is supplied by NIWA.
|Latest Version||CHES 4.1 for ArcGIS 10.6 (June 2018)|
|State of Development||Released and updated|
|Subdomains||Water Quantity/Flows, Water Yield|
|Intended End Users||
|Spatial Extents||Local (i.e. Catchment or District)|
|Steady State or Dynamic||Unknown|
|Level of Integration||Environmental|
|Key Input Data||Runoff, Land Use water allocation data, digital river network, ecological data|
|Input Data Formats||XLS(X), CSV, GIS compatible files|
|Key Output Data||Water quantity - reach-scale flow estimates under different water allocation scenarios|
|Output Data Formats||CSV, Image File(s), GIS Compatible Files|
|Open/Closed Source||Closed Source|
|Operating Systems||MS Windows|
|Software Needed||ArcGIS Need ArcInfo Desktop and Spatial Analyst licences|
|User Interface||Graphical desktop|
|Ease of Use||Moderate|
|Use in Policy Process||Plan (Policy Formulation), Review (Issue Identification)|
|Users Forum||Information updates to registered users|
|Methods included for managing uncertainty||In the simulation of flow time series data the option is available to set the level of uncertainty at 'low' or 'high' to provide a second flow time series in addition to the 'best estimate'.|
|Keywords||Water allocation, scenarios, water resource management|
|Linkages to other Models|
CHES - smarter use of New Zealand’s river waters: (https://www.niwa.co.nz/our-services/software-tools/ches-smarter-use-of-new-zealand%E2%80%99s-river-waters)
Managing water allocation on the West Coast: (https://www.niwa.co.nz/freshwater-and-estuaries/research-projects/managing-water-allocation-on-the-west-coast)
Hoyle J, Diettrich J and Franklin P. (2016): Applying the Cumulative Hydrological Effects Simulator (CHES) for managing water allocation: A demonstration of CHES in the Grey catchment, West Coast. Prepared for West Coast Regional Council.
This tool can be used to provide support to the management decisions on water allocation in a spatially complex region which experiences diverse water uses both in stream and out of stream.